Jim,
> ## You would need one heck of a lot of silicone to make one sheet for a
> chimney.
Not really! A chimney for a 4CX1500B, for example, would be about 8.2cm
inner diameter, and at most 10cm tall. Making it a half centimeter
thick, which is rather generous, you need 273ml of silicone caulk. A
310ml tube of silicone caulk costs about 3 dollars locally.
If you use smaller tubes, and use two of them, you still gen get the
chimneys for a legal limit amp from a single tube of caulk!
> Just buy the silicone rubber sheets from mc master carr in the usa.
> You roll it into a cylinder.. then use silicone rubber glue to glue the
> edges.
I'm certain that this is a good method. But for me, that method means
placing an import order and waiting 4 to 5 weeks for the items to
arrive. The silicone sheets I can get locally are just those sold in
supermarkets for kitchen use. They should do too, anyway... They are
intended to use in an oven, and are also rated for microwave ovens.
> Silicone rubber glue looks sorta like regular RTV glop.... but is high temp
> stuff,
> made for gluing silicone rubber sheets.
I would have to use plain silicone caulk for gluing. I haven't seen
dedicated silicone glue locally.
> The sheets are reddish colour. They will
> take a huge amount of heat. the sheets are also used in exhaust systems on
> trucks etc.
Any silicone can take a lot of heat! But some silicone is formulated to
take a little more heat than the basic one. I wonder if that reddish
colour is intrinsic to that high temp silicone, or if it is a dye added
to signal that this is high temp silicone!
> You can also get flexible silicone rubber hose... in large diam too.... used
> for front brake cooling
> on high performance cars. ( see it up to 3? so far).
Good to know.
Anyway, I mentioned my method of making silicone parts, because it is
useful for many things, not just tube chimneys. I have used this method
to make grooved insulating and shock dampening washers for variable
capacitors - a photo is in this page, about one third down the story,
http://ludens.cl/Radiohis/ak206/ak206.html
and also I have made spacers, angled insulating flexible holders, and
even some special size V-belts, in which I used cord to reinforce the
silicone. Having a few tubes of silicone caulk on hand, some
polyethylene stock to make molds, and tools, allows me to make special
parts rather quickly, instead of cobbling them together from parts I can
get ready made, or waiting a month or more for an import order to arrive.
> Alpha uses rolled up sheets too.
I have seen them, and wondered at their amateurish look, which I didn't
expect inside an amplifier of such high cost. But they work fine, so I
wouldn't complain...
Manfred
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